I didn't snorkel when pg with DS because my OB said it was best not to, but I think he was just confused about what was involved. I would definately snorkel if I had the chance during this or subsequent pgs - just don't breath-hold for too long, I'd say. But that said unless you are able to hold your breath for 30 seconds plus while swimming under water (not may non-scuba divers or experienced swimmers can) I can't see how it would be a problem.